Darwinia

The world of Darwinia is a virtual themepark, running entirely inside a computer network and populated by a sentient evolving life form called the Darwinians. Unfortunately Darwinia has been overrun by a computer virus which has multiplied out of control. Your task is to destroy the Viral Infection and save the Darwinians from extinction. Blurb from Introversion's website. Source: The Publisher Website.